Spheroidal shaped particles of aminoresin-silica polymeric composite

ABSTRACT

Spheroidal shaped particles of aminoresin-silica polymeric composite have been produced which possess an individual particle size range from 0.05 to 0.3 Mu . The composite particles contain from 70 percent to 99.5 percent aminoresin, the remainder being silica, the percentages expressed on a weight basis. These particles are usually aggregated into dense clusters of size from 1 to 10 Mu . These composites are useful in films and paper coatings.

United States Patent 1191 Emeta Nov. 5, 1974 SPHEROIDAL SHAPED PARTICLESOF 2,760,941 8/1956 AMINORESIN-SILICA POLYMERIC COMPOSITE 3:714:0851/1973 Berstein et a1. 260/39 SB Modesto Emeta, Princeton Junction, NJ.

Assignee: N L Industries, Inc., New York,

Filed: May 7, 1973 Appl. No; 358,046

Inventor:

US. Cl. 260/39 SB, 106/308 N 1m. 01 C08g 51/04 Field of Search 260/39SB; 106/308 N References Cited UNITED STATES PATENTS 8/1950 Veitch260/39 SB 10/1950 Powers et a1 260/39 SB Primary Examiner-Morris LiebmanAssistant Examiner-S. M. Person [57] ABSTRACT Spheroidal shapedparticles of aminoresin-silica polymeric composite have been producedwhich possess an individual particle size range from 0.05 to 0.3 u. Thecomposite particles contain from 70 percent to 99.5 percent aminoresin,the remainder being silica, the percentages expressed on a weight basis.

These particles are usually aggregated into dense clusters of size from1 to 10 y" These composites are useful in films and paper coatings.

11 Claims, N0 Drawings SPHEROIDAL SHAPED PARTICLES OF AMINORESIN-SILICAPOLYMERIC COMPOSITE Various types of microspheres or microcapsules havebeen produced for a variety of uses. Among those which are related tothe product of the instant invention-are urea-formaldehydemicroparticles having individual particle sizes ranging from 0.05 to 0.1p. which are formed as loosely adherent clusters having a cluster sizefrom l to y. and possessing surface areas up to 300 m lg. Such productshave been suggested for use as opacifying agents for paint, paper andthe like. These products have been used with limited success.

SUMMARY OF THE INVENTION The amino resin used in the instant inventioninclude aminoformaldehyde condensation products of urea, melamine,aniline, guanidine, thiourea and mixtures thereof. These aminoresins areformed and polymerized in the presence of polysilicic acid which formsaminoresin-silica compositions upon drying.

ln preparing these compositions the-following general procedure isemployed:

A watersoluble silicate solution is prepared which A preferably containsfrom 5 to 30 percent silicate, calculated as SiO An aqueous formaldehydesolution is used which preferably contains from 20. to 50 percentformaldehyde.

An aqueous amino solution is also prepared which contains from 0.5 to 2moles of the amino or amide for each mole of formaldehyde present in theformaldehyde solution.

The silicate solution, the amino solution and the formaldehyde solutionare admixed with rapid agitation. This mixture should contain less than5 percent sodium silicate by weight.

The mixture is then neutralized by adding an acid to the mixture untilthe pH falls within the range from- 6.5-9.

The neutralized misture is then heated to a temperature from 50C toboiling for about 4 hours during which time the polymerization takesplace. An acidic agent is again added to the mixture to lower the pH to1-6 and a white voluminous precipitate is formed.

The precipitate is the aminoresin-silica' polymeric composite. Theamount of silicate employed should be such that there is present from0.5 to 30 percent silica by weight in the final aminoresin-silicapolymeric composite.

In order to describe the instant invention in greater detail, thefollowing examples are presented:

EXAMPLE 1 An amino-resin-silica polymeric composite was prepared asfollows: i v

300 gms of a sodium silicate solution containing 25% SiO were mixed with840 gms of water. The mole ratio of the SiO to Na O was 3.75.

747 gms of a formaldehyde solution containing 36.5 percent formaldehydewere added to 150 gms of water.

360 gms of urea were mixed with 360 gms of water to form a ureasolution.

All of these three solutions were admixed with rapid agitation and thepH of the mixture was lowered to by the addition of concentrated HCl.

The mixture was then heated to 60C with stirringfor 2 hours, after whichthe temperature was allowed to drop to'25C. The pH of the mixture wasthen lowered to 3.5 with addition of 0.36% HCl. The temperature was thenraised to C and held at that temperature for 2V2 hours during which timea white voluminous precipitate of the polymeric composite was formed.The precipitate was then removed from the liquor by filtration andwashing.

Microcapsules having an individual particle size range from 0.1 to 0.2p. were produced. These microcapsules formed aggregates of denseclusters which were I to 10 p. in size. These clusters had a surfacearea of 36.7 mlg. These microcapsules contained percent ureaformaldehyde and 15 percent silica.

The operational details and the results obtained are recorded in thetable.

These microcapsules were employed as filler in paper. A standardprocedure was used to make a paper sheet containing 5 percent of thesemicrocapsules, plus 5 percent titanium dioxide pigment. The paper sheetwas compared to a standard paper sheet containing l0 percent titaniumdioxide pigment as the filler- It was found that the bulk density of thepaper sheet containing the microcapsules was reduced 24, percent overthe bulk density of the paper sheet containing only the titanium dioxidepigment and that only a slight reduction EX PLES ln these examples theprocedure of Example I was substantially repeated except that variousratios of urea formaldehyde to silica were used.

The operational details and the results obtained are. recorded in thetable'along with those of Example 1'.

EXAMPLES 5-7 The procedure of Example 1 was substantially repeated inthese examples except that various amino compounds other than urea wereused.

The details also are recorded in the table. When the microcapsulesproduced in Examples 2 7 were used in paper in the manner described inExample I 1, similar results were obtained.

While this invention has been described and illustrated by the examplesshown. it is not intended to be strictly limited thereto, and othervariations and modifications may be employed within the scope of thefollowing claims.

TABLE Example No. l 2 4 5 6 7 tRatsitbof Amino Resin 85/]5 95/5 90/l080/20 95/5 95/5 95/5 Amt of Na O. 3.75 SiO soln 300 I00 200 400 I65 I35284 containing 257: SiO-,.g Amt of H 0 added to Na,O. 840 280 560 2000 00 0 3.75 Si(); soln. g Amt of36.5'/1 Formaldehyde soln. g 747 745 745745 428 642 904 Amt of H 0 added to Formal- I50 I50 I50 150 0 0 0 dehydesoln. g

Conc 0.36% 0.3671 0.36% 98% 1071 l()% Type of Acid HCl HCl HCI HCI H,SOH- SO H 50. Adjusted pH 9 7 9 8 8 9 Urea/ Type of Amino group Urea UreaUrea Urea Thiourea Melamine Melamine l0/ Amt of Amino group. g 360 360360 360 304 378 10.7 Amt H 0 added to Amino group, g 360 360 360 3602000 2000 3600 Reaction temp. C 60 70-80 80 80 90 50 102 Time ofreaction. hr 2 1% 2 /2 4 4 2 lk H O addition. g 0 0 2000 0 0 350 0.367:0.36% 0.3671 0.36% 10 I071 l0'/1 Second Acid Addition HCL HCL HCL HCL HSO H 50 H 50 Adjusted pH 3.5 2.9 3.0 2.0 3 5.5 3.5 Temperature, C 80 8075 80 80 70 Room Reaction time, hr. 2% 3 3 l A 16 I claim:

1. A composition of matter comprising spheroidal shaped clusters ofaminoresin-silica polymeric composite particles having an individualparticle size range from 0.05 to 0.3 M, said particles formed intospheroidal shaped clusters of size from 1 to 10 t, said compositioncontaining from 0.5 to percent silica by weight, the remainder being theaminoresin.

2. Composition according to claim 1 in which the aminoresin is ureaformaldehyde.

3. Composition according to claim 1 in which the aminoresin is melamineformaldehyde.

4. Composition according to claim 1 in which the aminoresin is thioureaformaldehyde.

5. Composition according to claim 2 in which the amount of formaldehydeemployed is from 0.5 to 2.0 moles for each part of the amino groupemployed.

6. Process for producing spheroidal shaped clusters of aminoresin silicapolymeric composite particles which comprises admixing a solution of analdehyde, a solution of urea and a water soluble silicate solution,

9 Process according to claim 6 in which the the amine is thiourea andthe aldehyde is formaldehyde.

10. Process according to claim 6 in which from 0.5 to 2.0 moles offormaldehyde are employed for each mole of amine.

11. Process according to claim 6 in which the product possesses acluster size of from l to 10 a with an individual particle size of from0.05 to 0.3 t.

1. A COMPOSITION OF MATTER COMPRISING SPHEROIDAL SHAPED CLUSTERS OF AMINORESIN-SILICA POLYMERIC COMPOSITE PARTICLES HAVING AN INDIVIDUAL PARTICLE SIZE RANGE FROM 0.5 TO 0.3 $, SAID PARTICLES FORMED INTO SPHEROIDAL SHAPED CLUSTERED OF SIZE FROM 1 TO 10 $, SAID COMPOSITION CONTAINING FROM 0.5 TO 30 PERCENT SILICA BY WEIGHT, THE REMAINDER BEING THE AMINORESIN
 2. Composition according to claim 1 in which the aminoresin is urea formaldehyde.
 3. Composition according to claim 1 in which the aminoresin is melamine formaldehyde.
 4. Composition according to claim 1 in which the aminoresin is thiourea formaldehyde.
 5. Composition according to claim 2 in which the amount of formaldehyde employed is from 0.5 to 2.0 moles for each part of the amino group employed.
 6. Process for producing spheroidal shaped clusters of aminoresin silica polymeric composite particles which comprises admixing a solution of an aldehyde, a solution of urea and a water soluble silicate solution, neutralizing the mixture to a pH of 6.5-9, heating the mixture from 50*C to boiling to polymerize the mixture, acidifying the polymerized mixture to pH of 1-6, and precipitating the aminoresin-silica polymeric composite therefrom and recovering said precipitate as spheroidal shaped clusters of said composition, said composition containing from 0.5 to 30 percent silica by weight, the remainder being the aminoresin.
 7. Process according to claim 6 in which the the amino is urea and the aldehyde is formaldehyde.
 8. Process according to claim 6 in which the the amine is melamine and the aldehyde is formaldehyde.
 9. Process according to claim 6 in which the the amine is thiourea and the aldehyde is formaldehyde.
 10. Process according to claim 6 in which from 0.5 to 2.0 moles of formaldehyde are employed for each mole of amine.
 11. Process according to claim 6 in which the product possesses a cluster size of from 1 to 10 Mu with an individual particle size of from 0.05 to 0.3 Mu . 